In a bipolar junction transistor, the emitter efficiency is (p-n-p transistor):

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KVS TGT WET (Work Experience Teacher) 23 Dec 2018 Official Paper

\(\rm \frac{Current \ of \ injected \ carriers \ at \ J_E}{total \ collector \ current}\)
\(\rm \frac{Current \ of \ injected \ carriers \ at \ J_E}{total \ emitter \ current}\)
\(\rm \frac{Current \ of \ injected \ carriers \ at \ J_C}{total \ collector \ current}\)
\(\rm \frac{Current \ of \ injected \ carriers \ at \ J_C}{total \ emitter \ current}\)

Answer 1

Explanation:

Emitter efficiency

It is the ratio of current due to emitter majority carriers to the total emitter current.
Total current includes the sum of current injected at the emitter & current flowing from the base to the emitter junction ( minority carrier current.).It is always less than 1.

Additional Information

The heavily doped region will have a high injection factor because the base current can be neglected in comparison to the current injected into the emitter junction
In this case, Emitter Efficiency will be close to unity.